from burning CCA-Treated Timber
into Safer Incineration Methods
from burning CCA-Treated Timber
of CCA treated timber involves a number of environmental hazards.
Ash from CCA-treated timber contains elevated levels of heavy metals.
Once burnt, the ash continues to leach heavy metals. Solo-Gabriele
et al (2003a) confirmed CCA-treated wood ash exceeded the 5 mg/L
regulatory level for total arsenic leaching under the US EPA standards.
The CSIRO warns that the ash from burnt CCA-treated timber on rural
properties should be removed or buried away from stock, as the ‘salty
contaminated ash … can cause problems’ (CSIRO, 2002).
The smoke can also contains high levels of arsine gas and dioxins:
‘Studies show that, depending on the combustion conditions,
10-90% of the arsenic present in CCA-treated wood’ may go
up in the smoke (APVMA, 2003a: 47).
Australian research by Tame et al (2003), has tested ash from burnt
CCA-treated pine for polychlorinated dioxins (dibenzo-p-dioxins)
and furans (polychlorinated dibenzofurans, PCDD/F), well-known atmospheric
pollutants. They concluded that these pollutants formed mainly during
the smouldering of the char (ash), raising concerns about the impacts
after bushfires in residential areas, such as Canberra during 2002.
In Canberra 55 sites were contaminated with treated timber ash.
Site remediation required removal of 2000 tons of soil, took a year
to complete and cost around $3,000,000 (Godson, W. Pers. Comm.,
review recognised the risks associated with incineration and warned
that it ‘should only occur in very controlled facilities where
release of arsenic to the atmosphere is minimised and the potentially
highly toxic ash is processed and disposed of appropriately.’
For this reason the authority recommends that CCA chemical labels
be varied to prevent waste CCA-treated timber from being incinerated
(APVMA, 2003a, p.47). However because of its limited powers the
APVMA is not able to regulate potential incineration, although it
could have made recommendations on this.
of CCA-treated timber is in fact banned in some states including
NSW. EPA Victoria (2003) has raised concerns about horticulturalists
who burn waste such as CCA-treated timber and has fined at least
one grapegrower in 2003 for this because of the ‘significant
risk to human health, the environment and the clean green image…’
The South Australian EPA warns that ‘Children, pets and farm
animals should be excluded from land where CCA ash is present [for
example after bushfires]. Animals will want to lick or eat the salty
residue and young children, especially those under 5 years, are
at high risk from personal contact and ingestion. Animal deaths
from ingesting ash have previously been reported on farms in the
USA and UK’ (SA EPA, 2005).
timber may be incinerated accidentally as a result of house fires
and bushfires, or by people ignorant of its dangers when they dispose
of waste treated timber in backyard burn-offs. People can also put
treated timber into garbage streams that go to municipal incinerators.
Fire-fighting organizations such as the country fire services are
aware of the hazards associated with burning CCA but seldom know,
when they attend a fire, whether the burning timber is CCA.
of most concern is the fact that people sometimes burn it in their
indoor home fireplaces, without realizing the dangers that they
are exposing their families and neighbours to. Because traditional
sources of heating wood are becoming scarce and therefore more expensive,
scrap timber and off-cuts from building sites are turned to as free
sources of timber. ‘It is not uncommon to see this rubbish
wood, including treated pine etc, piled high in Canberra backyards…
not only treated pine but other treated timbers’ (Darryl Johnston,
Pers. Comm. 1/8/03).
timber may also be incinerated when it is mixed with other wood
that is used as fuel wood. Often waste wood piles contain some CCA-treated
wood, so that it would be hazardous to use them for fuel. Previous
research found that ‘visual sorting’, based on the colour
of the treated timber, is not accurate. To prevent the ash being
classified as hazardous in the US, wood reused for fuel must contain
less than five percent of CCA-treated timber (Solo-Gabriele, et
specific method for identifying CCA-treated timber is through a
stain test. Although this is a workable method, the cost and time
required to administer the stain were of particular concern to large
recycling facilities. Solo-Gabriele et al (2001) claim that the
Laser Induced Breakdown Spectroscopy (LIBS) and X-ray Fluorescence
Spectroscopy (XRF) that they are developing will provide a faster
and cheaper method for sorting waste wood. However both technologies
have technological drawbacks and are not ready for commercial use.
A trial of a portable hand held X ray device called a XRF metal
analyser is being used at Medley USA.
into Safer Incineration Methods
into safer controlled incineration methods that would capture the
arsenic and toxic residues has begun but it is in its early states.
At the University of Sydney’s Chemical Engineering laboratories,
research is underway into the possibilities of incinerating CCA-treated
timber to recover both the energy as well as the metals (as environmentally
stable residues). So far, the researchers have found that at temperatures
greater than 400°C the copper and chrome are contained in the
ash, while the arsenic is volatilized. The researchers are aiming
to recover all three metal components from the waste wood (Stewart
et al, 2004).
work undertaken at the University of Sydney for the Western Sydney
Waste Board, it was found that at a combustion temperature of 900oC,
energy was more efficiently produced than in pyrolysis and gasification
at lower temperatures, and arsenic (present as arsenate) was produced
in a stable form. The researchers noted that the arsenic produced
as off-gas was a concern, although if combusted in a flash smelter
such as those used in the copper industry, the arsenic could probably
be captured (CRESTA, 2000). Solo-Gabriele et al (2001) report that
in Europe pyrolysis technology appears to be further advanced, with
‘two full-scale pyrolysis operations’ in France which
claim to recover most of the heavy metals.
(2003a), The Reconsideration Of Registrations Of Arsenic Timber
Treatment Products (CCA And Arsenic Trioxide) And Their Associated
Labels (Review Summary), Australian Pesticides And Veterinary
Medicines Authority, Canberra. (pdf - 1.2MB)
CRESTA (2000), Copper chrome arsenate (CCA) Wood Waste: Review
of Thermal Options for CCA Wood Waste Management, Centre for Risk,
Environment and Systems Technology and Analysis, Department of
Chemical Engineering, University of Sydney, Sydney.
(2002), ‘CCA Facts’, Commonwealth Scientific and Industrial
Research Organisation website, http://www.ffp.csiro.au/wft/wpc/ccafact1.html
Victoria (2003), ‘Horticultural waste burning continues
to cause concern’, Media Release, 9 July.
EPA (2005), ‘Public Health Danger: Ash from CCA-Treated
Timber, Environmental Protection Authority, South Australia, 25
H., Khan, B., Townsend, T., Song, J-K., Jambeck, J., Dubey, B.,
Yang, Y-C., Cai, Y. (2003a), ‘Arsenic and Chromium Speciation
of Leachates from CCA-Treated Wood’, Florida Center For
Solid And Hazardous Waste Management, Florida.
H., Hosein, N., Jacobi, G., Townsend, T., Jambeck, J., Hahn, D.,
Moskal, T., Iida, K. (2001), ‘On-Line Sorting Technologies
for CCA-Treated Wood’, Draft Submitted on September 30,
for Sarasota County for Submission to the FDEP Innovative Recycling
M., Rogers, J., Breed, A., Haynes, B. and Petrie, J. (2004), ‘Deportment
And Management Of Metals Produced During Combustion Of CCA-Treated
Timbers’, Poster From The Environmental Impacts Of Preservative-Treated
Wood Conference, February 8-11, 2004, Orlando, Florida
NW, Dlugogorski BZ, Kennedy EM.(2003) ‘Assessing influence
of experimental parameters on formation of PCDD/F from ash derived
from fires of CCA-treated wood’, Environmental Science
and Technology 37(18): 4148-56.